Antiperspirant or deodorant compositions are employed on a substantial scale throughout the world in order to prevent or at least reduce the extent to which humans perspire, especially in certain areas of the body such as in the armpits or occluded areas such as on the feet and/or to control the extent to which body odours emanating particularly from such occluded areas are detectable by persons with whom the subject comes into contact. In many societies, there is a manifest desire to avoid the appearance of sweat under normal social conditions, and in particular sweat that penetrates clothing worn in close proximity to those areas and to prevent the generation of body malodours. Thus, cosmetic formulations have been developed to assist society to meet its need to control sweating and odour generated in selected body areas.
In one class of antiperspirant or deodorant formulation which is attractive to a significant fraction of consumers, an antiperspirant active is employed in the form of a particulate suspension in an anhydrous medium, normally a water-immiscible fluid. Such formulations allow activated aluminium chlorohydrate to be employed instead of standard aluminium chlorohydrate. This is beneficial because the activated material is more efficacious at controlling sweat than is the standard material, ie the user does not sweat as much in the body areas to which the formulation is applied.
Activated chlorohydrate is characterised by the presence of a significant fraction, particularly at least 20% of its aluminium in Band III species, as measured by the chromatographic method described in U.S. Pat. No. 4,359,456 (Gosling et al, assigned to Lever Brothers Company). The proportion of Band III species in an aluminium chlorohydrate antiperspirant is controlled by its method of manufacture, including in particular the reaction conditions under which polymeric aluminium chlorhydroxide species are formed and the conditions under which a solid, particulate product is formed. U.S. Pat. No. 4,359,456 describes conditions under which product can be made containing at least the minimum 20% Band III aluminium species.
The appearance of any cosmetic formulation is a factor of considerable importance to a consumer. He or she uses that appearance to judge its likely suitability for its intended purpose, sometimes using objective criteria and sometimes subjectively. Judgement is made more conveniently at various stages before or during application, the first being the appearance of the formulation in the dispenser, then possibly on the applicator surface of the dispenser and finally after application to the body. In the course of the research leading to the present invention, it was observed that certain anhydrous antiperspirant formulations containing a commercially available particulate AACH had a yellow appearance when viewed through the dispensing slits of the dispenser. This appearance is different from that of currently available antiperspirant formulations which are typically white and/or opaque. Accordingly, investigations were made to identify the source of the coloration and to find means to ameliorate or eliminate it. This problem of anhydrous formulations containing AACH exhibiting undesirable yellow colour has not been hitherto identified and accordingly no teaching has been given as to how to solve it, even in disclosures relating to the preparation of AACH for incorporation in antiperspirant formulations, possibly because it is not apparent in aerosol products in which the formulations are dispensed as a stream from metal containers.
It was found that the coloration of the anhydrous formulations containing particulate AACH was attributable to the AACH itself. There are many possible causes for a particulate material to be coloured, such as the presence of minor or impurity constituents, possibly even at trace levels. Low levels impurities are commonly encountered because commercial scale production of chemicals normally have to employ relatively impure reactants or solvents for them to be economically viable. However, the source was traced not to an impurity as such, but to the residual water content of the particulate AACH, or rather to a relative lack of water. By increasing its water content, it was found possible to reduce the discoloration of the anhydrous formulation containing the AACH.
However, the proposed solution to the problem of formulation discoloration caused by commercial AACH of increasing its water content itself poses a potential threat. High water contents cause AACH to lose its enhanced efficacy as an antiperspirant compared with standard aluminium chlorohydrate (ACH), and this has lead commercial producers of AACH to dry to low water contents to ensure the preservation of efficacy. In consequence, the problem addressed by the instant invention was not simply one of removing or eliminating the colour from anhydrous formulations containing AACH, but how to do so whilst preserving to at least a substantial extent the enhanced efficacy of AACH.
In U.S. Pat. No. 5,384,117, there is described a process for varying the refractive index of particulate aluminium chlorohydrate (ACH) by varying its water content. However, this specification provides no teaching of relevance to the present invention because it relates to ACH instead of AACH. The problem of yellow coloration with AACH clearly does not arise with ACH, otherwise the patentees would have mentioned it, since they were seeking to make clear gels. Moreover, the problem for AACH of impaired efficacy with increased water content does not arise for ACH since ACH is not an activated antiperspirant having high Band III content.
It is an object of the present invention to provide a product containing a composition of reduced colour as perceived by the human eye.
It is an object of one aspect of the present invention to obtain translucent anhydrous antiperspirant formulations containing AACH having a reduced or eliminated colour compared with formulations containing commercially available AACH whilst preserving to at least a substantial extent its antiperspirant efficacy.
It is a further object of an additional aspect of the present invention to provide a dispenser which co-operates with the formulation being dispensed therefrom to reduce or eliminate the colour of that formulation, as perceived by the eye.